SMC Networks SMC8150L2 manual Configuring Multiple Spanning Trees

3 Configuring the Switch

Configuring Multiple Spanning Trees

MSTP generates a unique spanning tree for each instance. This provides multiple pathways across the network, thereby balancing the traffic load, preventing wide-scale disruption when a bridge node in a single instance fails, and allowing for faster convergence of a new topology for the failed instance.

By default all VLANs are assigned to the Internal Spanning Tree (MST Instance 0) that connects all bridges and LANs within the MST region. This switch supports up to 65 instances. You should try to group VLANs which cover the same general area of your network. However, remember that you must configure all bridges within the same MSTI Region (page 4-152) with the same set of instances, and the same instance (on each bridge) with the same set of VLANs. Also, note that RSTP treats each MSTI region as a single node, connecting all regions to the Common Spanning Tree.

To use multiple spanning trees:

1.Set the spanning tree type to MSTP (STA Configuration, page 3-102).

2.Enter the spanning tree priority for the selected MST instance (MSTP VLAN Configuration).

3.Add the VLANs that will share this MSTI (MSTP VLAN Configuration). Note: All VLANs are automatically added to the IST (Instance 0).

To ensure that the MSTI maintains connectivity across the network, you must configure a related set of bridges with the same MSTI settings.

Command Attributes

•MST Instance – Instance identifier of this spanning tree. (Default: 0)

•Priority – The priority of a spanning tree instance. (Range: 0-61440 in steps of

4096; Options: 0, 4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864,

40960, 45056, 49152, 53248, 57344, 61440; Default: 32768)

•VLANs in MST Instance – VLANs assigned this instance.

•MST ID – Instance identifier to configure. (Range: 0-57; Default: 0)

•VLAN ID – VLAN to assign to this selected MST instance. (Range: 1-4094)

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